Hormonal Patterns Across the Menstrual Cycle
During the follicular phase, FSH, estrogen, and LH surge at ovulation; during the luteal phase, progesterone and estrogen are both elevated. 1
Follicular Phase Hormones
The follicular phase is characterized by a sharp increase in luteinizing hormone (LH), estrogen, and follicle-stimulating hormone (FSH) levels, with peak estrogen levels reached on days 12-14 of a normal menstrual cycle 2. This hormonal surge triggers ovulation through a positive feedback mechanism where high estrogen levels stimulate the hypothalamus to cause GnRH secretion, leading to massive LH secretion 2.
Key follicular phase hormones:
- FSH rises at the luteal-follicular transition, stimulating follicular growth and inhibin B secretion in the early follicular phase 1
- Estrogen progressively increases, reaching peak levels just before ovulation
- LH surges dramatically at mid-cycle to trigger ovulation
- Inhibin B is secreted during early follicular development
Luteal Phase Hormones
Following ovulation, the luteal phase is dominated by progressively increasing levels of both estrogen and progesterone until the mid-luteal phase 1. The corpus luteum becomes the primary source of these hormones, secreting progesterone, estradiol, and inhibin A in response to LH pulses, reaching peak secretion 6-7 days after ovulation 2.
Key luteal phase hormones:
- Progesterone is markedly elevated - this is the defining hormone of the luteal phase, with increased protein catabolism as a metabolic consequence 2
- Estrogen levels rise again during the luteal phase (secondary rise after ovulation) 2
- Inhibin A increases during the luteal phase
- Both hormones decline if pregnancy does not occur, triggering menstruation
Metabolic Implications
These hormonal fluctuations have significant metabolic effects. High estrogen levels during the luteal phase improve glucose metabolism by increasing glucose availability and glycogen storage in skeletal muscle, while also increasing free fatty acid availability and oxidative energy metabolism 1. Gluconeogenesis rates are higher in the follicular phase than the luteal phase at exercise intensities >50% VO2max 2.
The effects of estrogen on glucose metabolism are partly antagonized by progesterone, and high dietary carbohydrate intake can super-compensate muscle glycogen stores during the early follicular phase 1.